1. Technical Field
The following description relates to one or more techniques for an image forming apparatus configured to form an image of recording agent on a recording medium, in particular, for an image forming apparatus having an endless belt configured to convey one of the recording medium and the recording agent.
2. Related Art
Various kinds of image forming apparatuses have been proposed each of which includes an endless belt that is wound around a plurality of rollers having respective axes parallel to each other and configured to be driven to turn and convey a recording medium or recording agent. For example, an image forming apparatus has been known that includes an endless belt as an intermediate transfer belt. Specifically, the endless belt is configured to be driven to turn in contact with a plurality of photoconductive drums carrying respective toner images of respective colors, once carry the toner images sequentially transferred thereto from the photoconductive drums, and then transfer the toner images onto a recording medium such as a sheet. In addition, an image forming apparatus has been known that includes an endless belt as a transfer feeding belt. Specifically, the endless belt is configured to be driven to turn in contact with a plurality of photoconductive drums carrying respective toner images of respective colors and sequentially transfers the toner images onto a sheet being conveyed thereon in a superimposed manner when the sheet passes through respective nipping points between the photoconductive drums and the endless belt.
In the known image forming apparatuses, when the endless belt which is wound around the plurality of rollers having respective axes parallel to each other is driven to turn, the endless belt might gradually get close to one end in the axial direction of the rollers or turn in a snaking manner. In order to overcome the problem, such a technique has been proposed that a continuously-protruding strip-shaped guide is provided in a position, closer to one end than to the other end of the endless belt in the axial direction of the rollers, on the inner circumferential surface of the endless belt, and the guide is fitted into a groove formed on each roller. Further, in this case, such another technique has been proposed as to prevent ruffling of the endless belt by applying a greater urging force, for urging at least one of the rollers in such a direction as to provide a tension to the endless belt, to the one end of the at least one roller in the axial direction than to the other end such that the endless belt is urged to get close to the other end.